The present invention relates to a versatile storage device and holder for web material in roll form, from which the web material can be taken alternatively from the outer periphery of the roll or from a central cavity therein.
Many kinds of materials intended for many different uses are sold in roll form. Kitchen paper and toilet paper are each examples of material in roll form used on a daily basis. Gasoline stations, workshops and other places of work are normally equipped with holders which carry paper or some equivalent material for cleaning or drying the hands, wiping clean filler-cap openings or other dirty surfaces. Public toilets and similar buildings are also often equipped with paper towels in roll form.
When the web of material is paper, the web can be torn with relative ease, and the ease with which such webs can be torn is normally enhanced by the presence of perforations. In the case of webs of woven or non-woven fabrics, fiber cloth, it is necessary to provide the web with tear lines or weakenings along which the web can be torn, so that the web can be separated into pieces that are of a size suitable for the purpose intended.
When material is taken from a roll through the central cavity thereof, the material, at some stage in the life of the roll, will continue to unroll freely, in the absence of a pulling force, subsequent to withdrawing a piece of the material from the roll center. This is, of course, due to gravity, a fact which is of small comfort when a roll unwinds in this way, to leave the material in a heap on the floor.
An attempt has been made to overcome this problem with the aid of the invention disclosed in SE 8405108-5. The dispensing arrangement described in this publication is intended solely for unwinding a paper web axially from the center cavity of a roll.
In SE-B-8405108-5, the device which prevents the paper web from falling gravitationally from the roll has the form of an angled spring-loaded arm.
With regard to roll holders which are intended for supporting rolls from which material is unwound from the outer periphery of the roll, it will be observed that the radius of the roll constitutes a lever arm which, multiplied by the weight of the downwardly hanging material web, constitutes a turning moment which is counteracted by the friction engendered between the roll bobbin and its journal(s). This is most pronounced when the roll is full and thus presents the longest lever arm. When a piece of the web is drawn from the roll, the roll will rotate and generate inertia forces which can cause the roll to unwind. This problem is accentuated in the case of heavy rolls of relatively large diameter, such as paper rolls in public toilets and paper towel rolls in work shops for instance.
A further problem occurring with spindle-carried or bobbin carried rolls with which material is taken from the outside of the roll is that the friction in the bobbin bearing must not be so great as to cause the material web to be torn-off at inappropriate locations therealong when pulling off the web, i.e. so that excessively short lengths are obtained. This problem is particularly pronounced when the material web is perforated. If, on the other hand, the friction is too small, there is insufficient braking force to counteract the inertia forces generated by the roll as it is rotated by pulling off material from the outer roll periphery. Even when a desired length of web is torn off quickly, so that no material is left hanging from the roll to cause the aforesaid automatic unwinding of the roll, the inertia forces generated by rotation of the roll will maintain the roll in motion. The material will thus continue to unwind unhindered from the roll.